is cum. see-1st) This invention relates talmprovements in the method oi eiiecting the reaction oi alkali metals with aromatic hydrocarbons, and more specifically to a method oi eiieeting addition oi alkali metals to naphthalene and its homologues. This application is a continuation in part oi my co-pend-. ing applicatiom'serial No. 638,524 filed October a... alkali metals will me It is well known with a wide variety oi aromatic hydrocarbons under a wide variety oi conditions. An extensive review oi this work has been published by C. B.

Wooster, (Chemical Reviews x: 1 August 1832),

While most oi the reactions described are at present oi little technical significance on account oi the cost oi the materials involved, there is particular interest in the attempts that have been made to react alkali metals with the cheaper hydrocarbons such as naphthalene. Schlenk (Annalen 463 90-95) carried out slow reactions using lithium in ethyl ether and obtained sum-- cient reaction in eight days with naphthalene, and in fourteen days with diphenyl', to permit some examination oi the products ionned. He represented the alkali metal compounds by the iormulaa,

Bchlenk, using ethyl ether as solvent, iailed to get any detectable reaction of sodium with these hydrocarbons even in months. He attributed this to a poisoning eflect on the sodium' oi minute 179-187 1931), to be in all probability a monosodium tetralln iormed by addition oi iour atoms oi sodium to one molecule of naphthalene, iollowed by immediate ammonolysisoi-three atoms.

oi the sodium to sodamide as represented by the equations: v

CioHs+4N8-?C1 oHsNM Because oi the large consumption oi sodium and the reactivity oi the ammonia used as solvent, this method is practically useless as a means oi preparing acids or thaiene.

An object oi this invention is to provide a method ior causing alkali metals. and specifically other derivatives from naphsodium, to be added to naphthalene or its homo- 5 logues; a iurther obiect is to cause this reaction to be carried out at temperatures and \mder conditions iavorable to thestability oi the products; a iurther object is to-provlde a rapid reaction; my invention also includes the product or lo products iormed by the addition oi-sodium and potassium to naphthalene or its homologues. Other objects will appear irom the description oi the invention.

I have ioundthat certain solvents and classes oi solvents have a very specific action in promoting the reaction oi alkali metals with naphthalene to, form addition products. As stated, the action oi these solvents is specific, but I do not know whether their action is catalytic, whether the solvent itseli takes part in the reaction in some manner, or whether there are some solubility or other physical iactors involved.

The solvents which I have iound oi such remarkable activity and useiulness ior these reactions are broadly in the class oi ethers although all oi the ethers are not eiiective, and oi the eiiective ones, some are better than others. Thus although only a few. mono ethers are satis'iactoryas described and claimed in my co-pending application,

Serial No. 638,524, I have used satisfactorily aliphatic poly ethers oi all types. By poly ethers in this case I mean the fully alkylated products oi polyhydric alcohols such as the glycols and glycerols and including the ethers irom the hypothetical polyhydric alcohols such as methylene glycol or others with more than one hydroxyl group on the same carbon atom, e; g. ethyl ortho iormate, methylal or other acetals. Thus I have used successiully methylal; ethylene glycol diethers such as the methyl methyl, methyl ethyl, ethylethyl, 'methyl butyl, ethyl butyl, butyl butyl, butyl lauryl; trimethylene glycol dimethyl ether;

the case'oi ethers of the poly alcohols such as the glycerols they may have'ythe 0 on adjacent C atoms as in ethylene glycol or 1, 2 propylene glycol or they may be separated as in 1, 3 propylene glycol.

The chiei requirement of these poly ethers is that they must not react with the alkali metal or the alkali metal addition compounds under the conditions used. I do not mean by this thatthe :ethers may not react in some way in some reversible reaction with the alkali metal and/or 2 v naphthalene since indications are that the ethers in effecting the reactions may to some extent take part in the reaction, but the ether must not be broken up or form irreversible reaction products at a rate comparable with the desired.

,at rates very slow in comparison with the de-' sired addition reactions.

I have found that inert non-ether types of solvents such as hydrocarbons or alkyl sulfides which do not react with the alkali metals and which in themselves are non-effective for the reactions may be used as diluting agents for the effective aliphatic poly ethers. There is, however, a minimum concentration of the effective ether in the non-effective solvents beyond which the reaction will not proceed. Thus, in general the effective dimethyi ethylene glycol ether can be diluted with a non-reactive, non-effective hydrocarbon up to 4 or 5 times its volume. If the dilution be as high as 6 or 8 times the volume of the active ether the reaction will not proceed. With the higher mono ethers, which are non-effective or relatively non-effective in themsolves, the dilution may be greater.

I have discovered that alkali metals can be added not only to naphthalene but to various homologues of naphthalene by the method of my invention. For further description, the invention will be illustrated particularly with respect to the reaction of naphthalene with sodium, but it is to be understood that what is said thereon will apply equally well to the reaction, of the other alkali metals and to any of the naphthalene substitution products capable of forming addition compounds with alkali metals.

I have found that sodium reacts very readily with naphthalene in dimethyl ethylene glycol ether solution even at -70 C. Naphthalene also reacts readily with sodium using methyl ethyl glycol ether as solvent. Other mixed poly ethers with higher primary alkyl groups can also be used, as listed above.

It is to be understood also that this invention includes theuse as solvent, not only of the effective" solvents as defined and illustrated, but

also of mixtures of these solvents with other solvents which may include the less active higher mono ethers, and also hydrocarbons. Consider- HNa It is probable that this is an equilibrium reaction. It is also found that other isomeric disodium addition compounds are formed as evidenced by the formation of isomeric acids.

HNa

The soluble addition compound may involve the combination of disodium naphthalene'with an extra molecule of naphthalene in some other manner. Thus its formula could be written:

without specifying the exact method of combination. Moreover this soluble addition product may conceivably also include some combination with the ether solvent to account for the specific If such a solution which contains sodium equivalent to one gram atom of sodium for each gram molecule of naphthalene be treated with water or alcohol, it will yield equivalent amounts of naphthalene and dihydronaphthalene; with CO: it will yield the sodium salts of dihydronaphthalenedicarboxy acids,,along with an equivalent amount of naphthalene. If, however, either the hydrolysis or the carboxylation is carried out gradually while further amounts of sodium are present in the liquid, further amounts of this sodium will dissolve as that in the solution is used by the hydrolysis or carboxylation. In this manner I have been able to react essentially all of the naphthalene and recover the major amount as the dihydronaphthalene or dihydronaphthalenedicarboxy acids.

As indicated above, I have made this addition of sodium' to naphthalene itself and to its homologues such as alpha and beta methyl naphthalene. I have found that in the case of naphthalene itself, the product formed is in large part the 1:4 disodium compound. Formation of this compound is probably permitted by the splitting of the double bonds between the 1,2 and 3,4 positions and the formation of a double bond between the 2,3 positions with the sodium occupying the free linkages thus created. Such a mechanism would permit addition in a similar manner in the case of substituted naphthalene where the 1,4 positions may be occupied by constituent groups since the reaction is not dependent on replacement of hydrogen or substituents by the sodium; there is no hydrogen evolved in the reaction of my invention as far as I have been able to discover.

I have discovered that this sodium naphthalene addition product is a very reactive material. Thus. as indicated above, hydrolysis can be made to take placeto form dihydronaphthalene, .or

the addition product still in the ether solution can be treated with CO: and converted into out simultaneously in a single vessel.

acids, .which can .be isolated. The further reactions oi this sodium naphthalene addition product are not, however, claimed-in this application.

but are the subject matter of co-pending applications and applications to be filed at a later date.

In carrying out these reactions, I have found it to be of importance to have the surfaces of the sodium clean. Thus the solvent must'be purified of such materials as will react with sodium and tend to form insoluble coatings thereon. under the conditions to be used, and the sodium should be protected from contact with such reactive materials from the time it is mechanically subdivided. Extreme fineness of sodium is not required although the rate will be dependent, among other things, on the extentof sodium urface, and this affords one' means of controlling the rate. The naphthalene need not be of extreme purity. Technical flake naphthalene works quite satisfactorily. The complete absence of all sulfur compounds is not essential as shown by the fact that dimethyl sulfide can be used as an inert diluent solvent in the efiective reaction medium for the reaction of sodium with naphthalene. The presence of free CO: dissolved in the solvent is likely to interfere with the reaction of sodium with naphthalene starting because of coating the sodium. I

On the other hand, when the reaction is well started, dry C0: can then be introduced and the carboxylation carried on simultaneously as long as care is taken that the rate is insuilicient to destroy completely all the green color of the sodium naphthalene compound, which will continue to be formed by the reaction of additional sodium. In this way the preparation of the sodium salts of the dicarboxy acids can be carried I In order to insure complete freedom from metallic sodium in'the product, however, it is better to filter the green solution of the sodium naphthalene away from. the unreacted sodium and treat it with CO: in a separate vessel. 'I'his precipitates the sodium salts which can be filtered out and the solvent, together with unreacted naphthalene and a small amount of the sodium naphthalene compou'nd'returned to the first vessel. Such a process can be operated either as a batch process orcon- The concentration of naphthalene or its derivatives that can be used is limited only by its solubility. The reaction temperature can vary from at least 80 C. to above the melting point of sodium, limited only by the stability of the com- V bination of materials used and that of the prod- Example I v 100 c. c. of dimethyl ethylene'g lycol ether at room temperature were placed in a 'fiask and to this was added 19 gms. of fiake naphthalene and then 5.6 gms. of clean, finely divided sodium. The

- reaction commenced immediately ;upon adding the sodium as was evidenced by the solution turning an intensely green color. This solution was agitated continuously for about fifteen minutes and then a slow stream of CO: was introduced while the agitationwas continued; this stream ofCOswssmaintainedatsuchratethatthegreen color of the solution was not completely dis- 5 charged until the sodium had essentially all dissolved or reacted. Toward the end of two hours, the carboxylation was allowed to go to completion; the green color was completely discharged andinthevesselwasawhiteslurryofsodiumm salts of 'dihydronaphthalene-dicarboxylic acids.

. On treatment of the salts with aqueous H01 and repeated extraction with ether, a high yield of a mixture of the isomeric dibasic acids was isolated. The reactions are presumed to be essen- 15 daily quantitative although a portion of the acid is difiicult to extract from water. It is found that a considerable pcrtion'of the isomeric acids was the 1:4 acid. If carboxylation iscarried out at low temperatures, -60' C. to -80 0., higher so yields of. the 1:4 acid have been obtained. Other crystallisable acids are obtained in varying amounts, amongst which the 1:2 acid has been found to a considerable amount.

Example I! I A solution of 128 gms. of naphthalene in approximately 900 c. c. of purified diethyl ethylene glycol ether was agitated, in contact with 48 grams of sodium in the form of chips, the solution being 80 kept under a nitrogen atmosphere. The mixture was maintained at 24-26 C. and samples of the solution withdrawn at intervals for titrations of their sodium content: the sodium content of the solution is indicative of the extent of the reaction 88 since the sodium is insoluble in the reactants; This was determined by ilrst adding ex'cess methanol to the sample to react with the addition conipound and then titrating with standard acid.

The results showed the presence of 5.2 gms. so- 0 dium per liter at the end of one hour, 18.2 gms.

at the end of .two-and-one-half hours, and 21.7

gms. at the end of twenty-four hours. The rate in either case can be varied by such factors as the extent of sodium surface. but it becomes al- 4' most negligible when one gram atom of sodium has dissolved for each molecule of naphthalene in solution.

. Example III 11.6 gms. sodium and 39 gms. naphthalene were added to 375 c. c. glycol formal. The reaction started immediately. After fifteen minutes agitation. treatment with CO1 was begun as in Example I, and completed in two hours.

Example IV In order to demonstrate the ease of reaction of alkali metals with naphthalene and its homologues in a wide variety of polyether solvents a large number of experiments were carried out in a qualitative manner. A solution of naphthalene or its homologues in the ether was treated with the alkali metal preferably though not necessarily in contact with nitrogen instead of a air. and the metal surface scraped under the sclution if-necessary to start reaction. The formation of the characteristic colored compound in solution took place readily at ordinary temperature. Ethers tested in this manner for bringing about the reaction of sodium with naphthalene included the following: methylal; ethylene glycol diethers such as the methyl methyl, methyl ethyl, ethyl ethyl, methyl butyl, ethyl butyl, butyl butyl, butyl lauryl; trimethylene glycol dimethyl ether; glycerol trimethyl ether; glycerol dimethyl with alpha methyl naphthalene and with beta methyl naphthalene.

I claim:

. l. A method of eflecting the addition of an alkali metal to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the alkali metal and the hydrocarbon in a reaction medium which comprises a polyether derived from an aliphatic polyhydric alcohol, having all the hydroxyl hye drogen atoms replaced by alkyl groups, which ether is inert I both to the reagents and the products under the conditions of the reaction in suiflcient amount to promote the reaction.

2. A method of eil'ecting the addition or an alkali metal to an aromatic hydrocarbon of the' group consisting of naphthalene and its homologues which comprises reacting the alkali metal and the hydrocarbon in a reaction medium which comprises a fully alkylated polyhydric alcohol I which is inert both to the reagents and the products under the conditions of the reaction in sufficient amount to promote the reaction.

3. A method 01' eifecting the addition of an alkali metal to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the alkali metal and the hydrocarbon in a reaction medium comprising a glycol diether in an amount suiiicient to promote the reaction.

4. A method of eflecting the addition of an alkali metal to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the alkali metal and the hydrocarbon in-a reaction medium comprising a diether of a glycol having the ether groups on adjacent carbon atoms in an amount sufllcient to promote the reaction.

5. A method of eflecting the addition of an alkali metal to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the alkali metal and the hydrocarbon in a reaction medium comprising a polyether derived from analiphatic, trihydricalcohol, having all the hydroxyl hydrogen atoms replaced by alkyl groups, which ether is inert both to the reagents and the products under the conditions of the reaction in an amount sufllcient to promote the reaction.

6. A method of effecting the addition of an alkali metal to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the alkali metal 7 and the hydrocarbon in'a reaction medium comprising a glycerol triether in an amount sufficient to promote the reaction.

7. A method of effecting the addition of an alkali metal to an aromatic hydrocarbon of the group consisting or naphthalene and its homo-* logues which comprises reacting the alkali metal Lithium was shown to reand the hydrocarbon in a reaction medium which contains in suiilcient amount to promote the reaction a poly ether-of the group which consists of methylal, ethylene glycol diethers, trimethy1ene glycol dimethyl ether, glycerol trimethyl ether, methyl ortho formate, ethyl ortho formate, diethylene glycol methyl ethyl ether, formal of the monomethyl ether of ethylene glycol, dioxane, glycol formal, methyl glycerol formal and dimethylene pentaerythrite. 10

8. A method of effecting the addition of an alkali metal to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the alkali metal and the hydrocarbon in a reaction medium comprising an ethylene glycol diether in an amount sufficient to promote the reaction.

9. A method of eifecting the addition of sodium to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the sodium and the hydrocarbon in a reaction medium comprising a polyether derived-from an aliphatic polyhydric alcohol, having all the hydroxylhydrogen atoms replaced by alkyl groups, which ether is inert both to the reagents and the products under the conditions 0! the reaction in an amount sufllcient to promote the reaction.

10. A method of eflecting the addition of sodium to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the sodium and the hydrocarbon in a reaction medium which comprises a fully alkylated polyhydric alcohol which is inert both to the reagents and the products under the conditions of the reaction in sufficient amount to promote the reaction.

11. A method of effecting the addition of sodium 'to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues 40 which comprises reacting the sodium and the hydrocarbon in a reaction medium comprising a glycol diether in an amount sufilcient to promote the reaction. Y

12. A method of eifecting the addition of sodium to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the sodium and-the hydrocarbon in a reaction medium comprising a diether of a glycol having the ether groups on 5 adjacent carbon atoms in an amount suihcient to promote the reaction.

13. A method of eflecting the addition of sodium to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the sodium and the hydrocarbon in a reaction medium comprising a polyether derived from an aliphatic, trihydric alcohol, having all the hydroxyl hydrogen atoms 'replaced by alkyl groups, which ether is inert 0 both to the reagents and theproducts under the conditions of reaction in an amount sufllcient to promote the reaction. I

' 14. A method of effecting the addition of sodium to an aromatic hydrocarbon of the group 5 consisting of naphthalene and its homologues which comprises reacting the sodium and the hydrocarbon in a reaction medium comprisinga glycerol triether in an amount sufllcient to promote the reaction. 7

15. A method of effecting the addition of sodium to an aromatic hydrocarbon of the group consisting of naphthalene and its homologues which comprises reacting the sodium and the hydrocarbon in a reaction medium comprising in amounts suflicient to promote the reaction it poly ethylene glycol diether m an amount sufllcient ,to

16. A method of eflecting the addition oi. sodium to an aromatic hydrocarbon of the group consisting of naphthalene and its hemologues which comprises reacting the sodium and the hydrocarbon in a reaction medium comprising an promote the reaction.

17. A method of eflectlng the addition of sodium to naphthalene which comprises reacting the sodium and naphthalene in -a reaction me- 5 dium comprising an amount of ethylene glycol dimethyl ether suiilcient to promote the reaction.

It is hereby certified that'error appears ihfthe'printed specification of the sbove numbered patent requiring correetibn as follows: Page 1, second column, line 46, after the word and .semi-co1en,"ether;" insert formal; and

that the said Letters Patent should be read with this correction therein that the same may conform to the resord' of the 'case in. the Patent Office.